Labor and civil rights leader A. Philip Randolph led the protests that spurred desegregation of the US military. He was a key organizer of the 1957 prayer pilgrimage for civil rights, the 1958 and 1959 marches for school integration, and with Bayard Rustin organized the 1963 March on Washington, where Martin Luther King delivered his landmark "I Have a Dream" speech to an audience of a quarter-million.

He arrived in Harlem in 1911 to attend college, and after graduation he spent several years working in low-paying jobs and organizing a company of black Shakespearean actors. In 1925 he helped organize and became the first President of the Brotherhood of Sleeping Car Porters (BSCP), a union for all-black railroad workers of the Pullman Company. Pullman was one of the largest employers of African-Americans, but routinely required porters to spend up to ten percent of their work time performing unpaid clean-up duties, and barred promotion from porter to higher-paid jobs, which were reserved for whites only. Randolph affiliated the new BSCP with the Congress of Industrial Organizations, because the rival American Federation of Labor opposed equal pay and working conditions for blacks. Within three years more than half the company's porters were members of the union, but Pullman still refused to recognize the BSCP. The National Mediation Board did not certify BSCP until 1935, and Pullman finally signed a contract with the union two years later.

In 1940 and '41 Randolph traveled America, making well-attended and widely-covered speeches calling on blacks to stand together against the discrimination that left many jobs out of their reach. He called for a huge march on Washington for fair employment practices, but cancelled the march when President Franklin D. Roosevelt relented in June 1941 and ordered an end to discrimination in defense plant jobs. Randolph then organized the League for Nonviolent Civil Disobedience Against Military Segregation, and led protests calling for the complete desegregation of the US military. Seven years later this work again achieved success, with President Harry S. Truman's Executive Order 9981 of 26 July 1948, which read in part, "It is hereby declared to be the policy of the President that there shall be equality of treatment and opportunity for all persons in the armed services without regard to race, color, religion or national origin".

Always a Socialist, he was co-founder and publisher of the Socialist newsletter Messenger, later called Black Worker, and actively opposed World War I. Through the 1950s and '60s, Randolph was a respected elder statesman of the civil rights movement, and was frequently called upon to mediate policy disputes between various civil rights groups. His FBI file ran thousands of pages, and included an unsigned agent's notation describing Randolph as "the most dangerous black in America".